Yes, fever typically raises blood pressure temporarily
When you have a fever, your body is working harder to fight off infection or illness. Your heart beats faster, your blood vessels narrow, and your body releases stress hormones — all of which push your blood pressure up. This rise is usually temporary and goes away once the fever breaks and you recover.
The higher your fever, the more your blood pressure tends to climb. A mild fever of 100–101°F may raise your systolic pressure (the top number) by a few points. A high fever of 103°F or above can cause a more noticeable spike. This is your body's normal response to fighting infection, not a sign that you have developed high blood pressure as a chronic condition.
Key Takeaways
- Fever raises blood pressure temporarily because your heart works faster and your blood vessels tighten as your body fights infection.
- The relationship between fever and blood pressure is direct: higher fevers usually cause larger blood pressure increases.
- Blood pressure returns to your baseline once the fever resolves and you recover from the underlying illness.
- If your blood pressure stays high after your fever is gone, or if you have other concerning symptoms, talk to your doctor about what may be causing it.
- Treating the fever with rest, fluids, and fever-reducing medication can help bring both your fever and blood pressure back down.
Why fever and blood pressure rise together
Your body raises its temperature on purpose when fighting an infection. This higher temperature helps your immune system work more effectively against bacteria or viruses. To maintain that higher temperature, your body needs to increase blood flow and metabolic activity throughout your system.
Several things happen at once during a fever. Your heart pumps faster to move blood more quickly through your body. Your blood vessels constrict (narrow) to keep heat in and maintain the higher core temperature. Your nervous system releases adrenaline and other stress hormones that make your heart work even harder. All of these changes push blood pressure upward as a side effect of the fever itself.
This is different from chronic high blood pressure, which develops over time and persists even when you are not sick. A fever-related blood pressure spike is acute — it comes on quickly and goes away when the fever ends.
How much blood pressure typically rises with fever
The amount your blood pressure rises depends on how high your fever climbs and how your individual body responds. Research shows that for every 1°C (about 1.8°F) increase in body temperature, systolic blood pressure can rise by roughly 1–2 mmHg on average. However, this varies from person to person.
Someone with a low-grade fever of 99–100°F might see almost no change in blood pressure, or a change of just a few points. Someone with a fever of 104°F might see their systolic pressure jump 10–15 points or more above their normal baseline. People who already have high blood pressure may experience a larger spike than those with normal baseline readings.
The important thing to remember is that this rise is expected and temporary. Once you recover from the infection and your temperature returns to normal, your blood pressure should come back down to where it was before you got sick.
When to monitor your blood pressure during illness
If you have a history of high blood pressure or heart problems, it makes sense to check your blood pressure while you have a fever, especially if the fever is high or lasts more than a day or two. This gives you a baseline to compare against once you recover. Write down the readings along with your temperature and the time of day, since blood pressure naturally varies throughout the day.
You do not need to check constantly — once or twice a day is usually enough. If you do not have a home blood pressure monitor, many pharmacies offer free blood pressure checks, or you can ask your doctor's office to check it during a visit.
Keep in mind that taking your blood pressure while you are anxious, in pain, or uncomfortable can give a higher reading than your actual pressure. Try to rest for at least five minutes before checking, sit with your feet flat on the floor, and use a properly fitting cuff.
How to bring fever and blood pressure down
The most direct way to lower both your fever and blood pressure is to treat the underlying infection and let your body recover. Rest is essential — your body needs energy to fight off illness, and stress from activity can keep your blood pressure elevated.
Staying well hydrated helps your body regulate temperature and supports your cardiovascular system. Drink water, broth, herbal tea, or other clear fluids throughout the day. Dehydration can actually make both fever and blood pressure worse.
Over-the-counter fever reducers like acetaminophen or ibuprofen can lower your temperature and may help bring blood pressure down as a result. Follow the package directions and do not exceed the recommended dose. If you are taking blood pressure medication, check with your pharmacist or doctor before adding any fever reducer, since some can interact with blood pressure drugs.
Dress lightly and keep your environment cool to help your body shed excess heat. Avoid heavy blankets or overdressing, which can trap heat and keep your fever higher.
When fever-related blood pressure is a concern
In most cases, a blood pressure rise from fever is not dangerous and resolves on its own. However, a few situations warrant attention from a doctor.
If your fever is very high (above 104°F) and accompanied by severe headache, chest pain, confusion, or difficulty breathing, seek medical attention right away. These can be signs of a serious infection that needs treatment beyond home care.
If your blood pressure stays elevated even after your fever has been gone for several days, or if you develop high blood pressure readings when you are not sick, talk to your doctor. This could signal that something else is going on with your cardiovascular health.
If you have a known heart condition or take blood pressure medication, let your doctor know when you have a high fever so they can advise you on whether any adjustments to your routine are needed.
The difference between fever-related and chronic high blood pressure
A temporary blood pressure spike during a fever is not the same as having high blood pressure as a chronic condition. Chronic high blood pressure (hypertension) persists over weeks, months, and years, even when you are healthy and not fighting an infection. It develops gradually and often has no obvious symptoms.
Fever-related blood pressure elevation is acute, predictable, and tied directly to your body temperature. It comes on quickly when the fever starts and goes away when the fever ends. Chronic high blood pressure requires ongoing management with lifestyle changes, medication, or both.
If you notice that your blood pressure is high during a fever but returns to normal once you recover, that is a normal response to acute illness. If your blood pressure readings remain high across multiple visits when you are not sick, that is when your doctor may diagnose chronic hypertension and discuss treatment options with you.
Frequently Asked Questions
Does every fever raise blood pressure?
Most fevers do raise blood pressure to some degree, but the increase may be small enough that you would not notice it without measuring. Very mild fevers might cause little to no change. Higher fevers almost always cause a noticeable rise. Individual responses vary based on age, overall health, and whether you already have high blood pressure.
Can fever cause permanent high blood pressure?
No. A single fever or even repeated fevers from common illnesses do not cause lasting high blood pressure. Once you recover and your temperature returns to normal, your blood pressure should come back down to your baseline. If your blood pressure stays high after recovery, the cause is something other than the fever itself.
Should I take blood pressure medication during a fever?
Continue taking your regular blood pressure medication as prescribed unless your doctor tells you otherwise. Do not stop or change your dose because of a fever. If you are concerned about how the fever might affect your medication, call your doctor or pharmacist for guidance.
What if my blood pressure is very high during a fever — is that an emergency?
A high blood pressure reading during a fever is usually not an emergency by itself. However, if the high reading is accompanied by chest pain, severe headache, shortness of breath, vision changes, or confusion, seek medical attention. These symptoms together can indicate a serious condition that needs when ready care.
How long does it take for blood pressure to return to normal after a fever breaks?
Blood pressure typically begins to drop as soon as your temperature starts coming down, and it usually returns to your baseline within a few hours to a day after the fever resolves completely. If your blood pressure is still elevated several days after your fever is gone, contact your doctor to rule out other causes.